^ 



Q45 



U. S. DEPARTMENT OF AGRICULTURE. 

BUREAU OF ENTOMOLOGY— BULLETIN No. 59. 

L. O. HOWARD, Entomologist and Chief of Bureau. 



PROLIFERATION 



AS A FACTOR IN THE NATURAL CONTROL 



OF THE 



MEXICAN COTTON BOLL WEEVIL. 



BY 



W. E. HINDS, Ph. D., 

In Charge of Cotto)i Boll Weevil Lahoratoi-y. 



Issued August 27, 1906. 




WASHINGTON: 

C40VERNMENT PRINTING OFFICE. 

1906. 



Ikmognifib 



V, 



Bui 59, Bureau of Entomology, U, S Dept. of Agricultur 



Plate I. 




Proliferation from Weevil Feeding-punctures. 

Fit; 1 — KiKlit halt of square tilled with granular M,pi>eann,t; pniliforatioii. enlar,i,a'(l four diame- 
ters ¥)K 2— Interior of square, proliferation from feeding puncture dru'd and brown, 
enlarged two diameters. Fig. 3.— Seetii>n throu,gh feeding puncture trom whicli proliteration 
spread to tip of .Miuare. enlarged four liiaineters. Fig. I — Pn>liferation starting from teedmg 
punctures in tjoUs, enlarged two diameters. (Original ) 



U. S. DHPARTMFNT OF AGRICUITURE. 

BUREAU OF ENTOMOLOGY- BULLETIN No. 59. 

L. O. HOWARD, Entomologist and Chief of Bureau. 



PIIOLIFKKATION 



AS A FACTO Pt IN TflE NATliRAL CONTROL 



MEXICAN COTTON ]]OLL WEEA^IL. 



W. E. HINDS, Ph. D., 

1)1 ('lt(irt/t' of Ciil/iiii J!(il/ ]]'ii'ri/ Lnhiinitiin/. 



IsfiUEU August 27, 190(i. 




WASH1N(tT()N: 
a o v e k n m k n t p 11 1 n t inc office, 

il»(M). 



^^onograph 






LIHTRR OF TRANSMITTAL 



U. S. Department of Agriculture, 

Bureau of Entomology, 

WasJiington, D. C, April 10, 1006. 
Sir: I have the lionor to transmit herewith a manuscript prepared 
by Dr. W. E. Hinds, special field agent of this Bureau, engaged in 
work on the boll weevil. This manuscript is a study of the pro- 
liferation in the squares and bolls of cotton by means of which a 
certain percentage of weevil larvae are killed. It does not deal at 
length with the botanical aspects of the (luestion, Init is rather a 
practical statement of the effect of this formation of loose tissue cells 
upon the boll weevil, based upon a large number of observations 
made by agents of the Bureau of Entomology. The botanical side 
of this phenomenon has been fully considered by Mr. O. F. Cook, 
of the Bureau of Plant Industry, and this paper is therefore supple- 
mental to papers published by Mr. Cook on this subject. The preface 
is written by Mr. Hunter, and the conclusions in the paper have 
been revised by him. In addition to the general interest in the sub- 
ject, the information given will be undoid:)tedly of distinct advantage 
to those engaged in cotton-breeding work, and I therefore recommend 
that it be issued as Bulletin No. 59 of this Bureau. 
Respectfidly, 

C. L. Marl ATT, 
Acting Chief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 
2 



U. 01 y* 



PREFACE 



Aside from the hal)it of determinate growth, perhaps the most 
im]^ortant tendency of the cotton plant that has the effect of avoiding 
damage l)y the l^oll weevil is that of proliferation in the stpiares and 
bolls, which was first observed by Dr. W. E. Hinds in 1902 at Vic- 
toria, Tex. The present paper places on record a large number of 
observations and exj>eriments relating to this phenomenon, which 
have been carried on for several years by the boll-w(^evil investigation 
in Texas. The studies upon which the paper is based were planned 
primarily to determine the ways by which jn-oliferation actually 
affects the weevil. Other features of })roliferati()n have l)een dealt 
with fidly by Mr. (). F. (\iok, whose ])ublications are referred to more 
s])ecifically in the text. In addition to the general interest of the 
information given, nuu-h of it will undoubtedly be of special advan- 
tage to those who are engaged in cotton-breeding work. 

As will be seen in the following pages, it has been ascertained that 
the rate of mortality among weevils in s([uares of American u])land 
varieties of cotton is higher by about 13.5 per cent as a result of {)r()- 
liferation. This in itself is of no little significance, but it is to be 
noted that the greatest importance of proliferation is in connection 
with some of the foreign varieties of cotton, which seem to have 
this property develo])ed to a much greater extent than the American 
upland varieties. Consecpienth^, the discoveries of j\lr. O. F. Cook, 
relating to the Kekchi cotton of Guatemala and the possibility of 
utilizing this cotton in the Ignited States, are of great interest. 

An important didiculty which will be encountered in the work 
of breeding cottons which proliferate to a great extent, will he the 
capability for adaptation on the ])art of the boll weevil. That this 
insect has consideral^le ca]iability for ada])tation is shown in the 
great variation in the size of the adults, the result of conditions of food 
supply in the immature stages to which it has adapted itself, as well 
as in man}" other ways. As a matter of fact, the capacity of the weevil 
for ada})tation is probal)ly fully as great as is the natural adaptive 
capacity of the cotton plant. Nevertheless, the interference of man 
may throw the advantage greatly in favor of the plant. 

The work upon which this publication is based was ]>erformed 
under the general direction of the writer by Dr. W. E. Hinds. He 
was assisted hi various ways by practically all the agents of the boll- 
weevil investigations, but more ])articularly by Messrs. A. C. Morgan, 
W. W. Yothers, W. Dwight Pierce, A. W. Morrill, and F. C. Pratt. 

W. D. Hunter, 
//(- (liargc of Cotton Boll Weevil Investigations. 

' 3 



ro XT 1: NTS 



PilgO. 

liii rodiirl \nn. 7 

Eiiiliest ohsoi'vaf ions. 7 

Sc()[)t> oi" pn^scMil (lisciissii)ii. .... 7 

Dcfinitioiis 8 

Metliod of study !) 

Proliferation from fccdin"^ puncliirc-: in si|uai(' ^ K? 

Pfolifcralion from fccdin;:; |>unclui('s in hoils ... 11 

Tiiflncncc of di(r<'i(Mil localit ics and s(>as<)ns 12 

Ohsci'valiciis on s(|Uar('s 12 

Ohscrvalions on Ix.lis II 

EflVcts of climatic conditions 15 

l<]llcct on proliferation of fei'tilizin;'; 1 lie roil . 17 

I'roliferation foilovvin<z; oviposition in : lUares . . 21 

Summarv of rcM'ords foi- four varici ic ■, 24 

Increase of niorlalitx- accom])an\ iuf; more scxcic attack ....... 2P> 

Increased mortalit \' in s(|uarcs and ixills dxiv i o prolifcral ion. . 2() 

vSummary of results of ol)scr\ations 27 

Formation of proliferation 27 

Increased mortality of \vec\il sta^jes due to prolifcral ion 2S 

Stinuilation to proliferation \>v causes ol licr i liau wccxil at taci< 29 

Proliferation slinudaled hv otiiei- insects 29 

Prolifei'alion stinuilated by attacks of fmiiji 29 

Artificial stinuilation to prolifcral ion. * 'AO 

Metliod of treatment '.iO 

Results with s(|uares 'M 

Results with holls :)2 

Comparison of icsulls from simi)le needle punctures wilh ell'ects of chemical 

injections 31 

(V)mparis()n of results from s(>alcd and unsealed j)vmctures 34 

Conclusions 35 

Maiuier in which proliferation causes death of wee\il sta<i;es . 35 

Roarino; larva' on purely proliferous food 35 

Mechanical crushing the real method 3() 

Explanation of mechanical action 37 

Proliferation in plants other than cotton 38 

Conclusions as to nature and significance of prolih>ration 38 

Practical application of conclusions from this st udy 39 

Index 43 

5 



ILLUSTRATIONS 



PLATES. 

Page. 

Plate [. Fig. 1 . — Granular appearance of proliferation Frontispiece 

Fig. 2. — Proliferation among anthers following feeding puncture. . .Frontispiece 
Fig. 3. — Proliferation following weevil feeding puncture in scjuare. .Frontispiece 

Fig. 4. — Proliferation following weevil feeding puncture in boll Frontispiece 

ir. Fig. 5. — Bollworni full-grown, feeding on boll 2S 

Fig. (>. — Punctures of small i)ollworni in sf|uare, proliferation protruding. 28 

Fig. 7. — Scpiarc-liiirer at work 28 

III. Fig. S. — Boll fed on bv bugs, showing no external injury 28 

Fig. '.I. -Insidr of carix'l sliown in lig. S, pi-oliferalion starting 28 

Fig. 10. —Section of boll fed u]ion by Pcutatonia Jujatd, proliferation in 

seeds 28 

Fig. 1 1 . — Sect ion of proliferated seed 28 

Fig. 12. — Poll showing anthracno.se disease which may cause proliferation . 28 

IV. Fig. V.i. — Proliferation in seeds from artiiicial injection of water 30 

Fig. 14. —Proliferation in cai-jiel and seed from artiiicial injection of acetic 

acid 30 

Fig. 1'). — Prolifcralion eii\ ('lo|)iiig lar\;i in l)oll 30 

Fig. ](). — P>oli buist o])en l)y inteinal i)ressure of proliferation 30 

V. Fig. 17. — Numerous proliferations starting on inner sides of carpels 36 

Fig. IS. — Proliferation pushing into pupal cell, pressing upon pupa 36 

Fig. U). — Adult weevil deformed by pressme of proliferation 36 

Fig. 20. — Ma.ss of proliferous cells upon inside of carpel 36 

VI. Fig. 21. — Ijocks completely filled with proliferation; a, original egg punc- 
ture ; h, larva surrounded and crushed to death 36 

6 



PROLIFERATION AS A FACTOR IN THE NATURAL CONTROL OF 
THE MEXICAN COTTON BOLL WEEVIL. 



INTRODUCTION. 

EARLIEST OBSERVATIONS. 

Soon after the beginning of the hiboratory work upon the cotton 
boll weevil at Victoria, Tex., in 1902, it was noticed that the attack of 
th(> weevil was frequently followed ])y a very decided change in the 
structure of the tissues near the point of attack in both l)uds and bolls. 
The significance of this change was not at that time fidly appreciated, 
and the observations made upon the weevil did not include records as 
to the occurrence and effect of this phenomenon. For this reason the 
early observations made before the autunm of 1903 have furnished 
comparatively little material which could be used in making tabular 
stAtements, such as have been made from more recent studies of the 
effect of proliferation upon the development of the boll weevil. 

When and by whom proliferation was first observed in cotton is not 
known to tlie writer, ])ut no publication relating to this phenomenon 
prior to that made in Bulletin No. 45 of the Bureau of Entomology, 
pages 96 and 97, has been found. The earliest notes upon the occur- 
rence of proliferation and its effect upon the weevil were made by the 
writer in September, 1902. Since that time there has been gradually 
accumulating in the notes of the agents of the Bureau of Entomology 
who have been studying the boll weevil, a large amount of data bearing 
ujion this subject. 

In the plans made for the .work of 1904, at the beginning of the 
season, definite provision was made for ol)servations upon this phe- 
nomenon in a munber of varieties of cotton and for testing the 
infiuenco of fertilizers in stimulating a greater manifestation of prolif- 
eration in the plants treated. Since that time the observations upon 
proliferation and its effect upon weevil development and injury liave 
been carried on continuously. 

SCOPE OF PRESENT DISCUSSION. 

The present paper does not pretend to l)e a study of proliferation in 
the botanical aspects of the question, Imt rather a practical statement 
of the large number of observations made by agents of the Bureau of 
Entomology primarily regarding the effect of this formation of loose 

7 



I'ROLIFERATION IN CONTROL OF KOLL WEEVIL. 

tissue cells upon the l)oll weevil. It is consequently of an entomolog- 
ical and not a botanical character. The botanical significance of the 
phenomenon has been very fully considered by Mr. O. F. Cook, of the 
Bureau of Plant Industry, to whose publications among those listed 
below" the r(>a(ler is referred for a discussion of that part of the subject. 

DEFINITIONS. 

In order that the statements here made may be readily understood 
by one who is not familiar with terms used in botany <»r entomology 
a few general definitions may be in order. In Bulletin No. 45 of the 
Bureau of Entomology, concerning the cotton boll weevil, the term 
"gehitinization" was used instead of ])roliferation, as it was believed 
that its significance woidd be b(>tter understood by the average reader, 
though it was realized that, strictly speaking, the term used expressed 
an incorrect idea, concerning the nature of the change^ to which it 
referred. The term "proliferation" is in general use both in botany 
and zoology, to denote a growth by the multiplication of (dementary 
parts. In the ])resent case we may define proliferation as being the 
development of numerous elementary cells from ]^arts of the bud or boll 
which are themselves normally th<^ ultimate product of combinations 
of iimch more highly sjiecialized cells. The resulting product is thus 
composed of comparatively large, thin-walled cells, which are placed so 
loosely together that the residting formation is of a soft texture, and 
has a granular appearance (PI 1, fig. 1) which may be ]^lainly seen 
with the unaided eye. The soft, ])uli)y nature of this growth led to the 
choice of the term" gelatinization" as being most appropriate to signify 
in a general way its appearance and texture. It appears that this forma- 
tion may originate from various causes in almost any part of the bud or 
boll (Pi. I, figs. 2-4). Whatever may have been the inciting cause, the 
character of the formation a])pears very much the same in any case. 
Ihidoubtedly, however, certain tissues proliferate more readily than 
do others. In squares, the outer layer of the column upon which the 
stamens are borne appears to be especially susceptible to stimuli which 
produce this reaction^ In bolls, the cells immediately adjoining the 
thin, hard layer lining the hulls or carpels are most frequently the 

o Bibliography of l-*iolil'eration: 

1904. Hiintcf, W. D., and Hinds, W E.— Tlie Mexican Cotton Boll Weevil. Bui. No. 
45, Biueau of Entoni()lop;y, I'. S. Dept. Agnc, pp. 9(5-97. 

1904. Cook, () P.— Evolution of Weevil Resistance in Cotton. Science, Vol. XX, pp. 
666-670. 

1905. Hunter, W. I)., and Hinds, W. E.-~15ul. No. 51, Bureau of Entomology, U. .S. 
Dept. Agric, pp. 133-134. 

1905. Cook, O. F.— Cotton Cidture in (Juateniala. YearlM)ok U. S. Dept. Agric, f. 
1904, pp. 47r>-4cS8. 

1906. Cook, (). F.— Weevil Resisting Adaptations of the Cotton Plant. Bui. No. 88, 
Bureau ot Phinl industry, V. S. Dept. Agric. 



METHOD OF STUDY. 9 

point at which proHforatioii begins. In most cases the prohfcration 
appears to begin very near to the point of injury, but from that point 
it may spread tlu'oiigh an entire lock, or to all the inner parts of an 
injured bud. 

METHOD OF STUDY. 

As the significance of these observations came to be more fully 
appreciated it was believed that they contained at least a suggestion 
as to some very promising lines of work in the problem of controlling 
the weevil. Accordingly, it has been necessary to study carefidly the 
nature of the phenomenon, conditions of climate, soil, fertilizer, and 
variety of cotton which affected the occurrence of proliferation. 
Observations have, therefore, been made ujjon (piite a large number of 
varieties, and in locations ranging from Victoria to Dallas, Tex., upon 
various t^^pes of soil, and in connection with various exi)eriments with 
fertilizers and different conditions of cultivation. From a comparison 
of the results thus ()l)tained it was hoped that some factors might be 
found which coidd be used ])ractically in increasing proMferation, and 
thus rendering it more effective as a factor in controlling the weevil. 
In many cases the results of the work have been quite different from 
those anticipated, but enough has been learned to justify the assertion 
that at present proliferation is a more important factor in retarding the 
nmltiplication of the weevil than are the parasites which have thus far 
been found. 

Large munbers of squares and bolls have been carefidly examined 
in obtaining these records. In the examination of bolls, the lock 
has been made the unit rather than the l)oll. As a general rule, a 
larva confines its injur}^ almost, if not entirely, to the lock within 
which the egg was originally placed. Quite frequently two or more 
larvc^ occur within a lock, but even in such cases the injury does not 
often extend through the septum or partition which separates the 
locks. 

In making a comparison of varieties considerable care is recpiired 
in subdividing the classes of observations in order to render the influ- 
ential conditions sufiiciently imiform to make the observations fairly 
comparable and wherever possible to reduce the fundamental causes 
or stinndi producing variations in the proliferation to one essential 
factor. While the phenomenon in bolls is of a similar nature to 
that in scpiares, conditions in these -two cases are so ditferent that 
the results are not strictly comparable, and therefore separate tables 
have been made for squares and bolls. The effects of feeding and 
egg punctures also call for separate classification. Tliis treatment 
of the subject necessarily multiplies the number of tables, but we 
hope that it will render the results more easily intelligible. The 
personal ecpiation of the observer has been ecpialized by combining 
the records made by a nund)er of investigators. 
31022— No. 59—06 ^2 



10 prolifp:ration iisr control of boll wep]vil. 

PROLIFERATION FROM FEEDING PUNCTURES IN SQUARES. 

As the sfjuare precedes the boll in the natural process of develop- 
ment and the feedin^i; puncture precedes oviposition in the attack 
of the weevil, wc shall consider first the observations regardino; pro- 
liferation resulting from feeding punctures made in squares. These 
observations include nearly 25 varieties of cotton. They are grouped 
by years and localities in order to bring as closely together as is possi- 
ble those records which may be considered as most strictly compar- 
able. The totals and averages for so many seasons and localities 
should constitute a very fair average statement of the true condition. 

Table L — Proliferation resulting from feeding punctures in squares — comparison of 

varieties. 





Locality. 

• 


Variety. 


Total 
number 
of punc- 
tured 
squares 
exam- 
ined. 


Squares with 
proliferation. 


Squares with no 
proliferation. 


Date. 


Num- 
ber. 


Per 
cent of 
total. 


Num- 
ber. 


Per 
cent of 
total. 


1902. 
Sept. 17 

1903. 

July 8 

to 




Several varieties 

King 


16 

470 

83 

102 
101 
79 
74 
82 

78 

53 
10 
21 
70 
33 
47 
45 
69 
25 
39 
36 
IS 
30 
27 
34 
31 
34 
163 


4 

286 

49 

38 
67 
59 
35 
62 

42 

8 
3 

15 
14 
23 
28 
32 
11 
22 
18 

7 
15 
15 
15 

4 
16 
71 


25.0 

60.1 

59.0 

37.3 
66.3 
74.3 
47.3 
75.6 

53.8 

15.1 
30.0 
29. G 
21.4 
42.4 
48.9 
62.2 
46.4 
44.0 
56.4 
50.0 
38.9 
50.0 
55.6 
44.1 
12.9 
47.0 
43.6 


12 75.0 


I do 


184 1 39.9 


Oct. 28 

Aug. 10 

to 


I do 


Parker 

Mascot 


34 41.0 


Oct. 19 
Oct 25 


1 

do 


64 
34 
20 
39 
20 

36 
45 


62.7 


Do 


do 


Dickson 


33.7 


Oct '^4 


do 


Mit Aflfl .. 


25.7 


Oct '^2 


do 


Ashmouni 


52.7 


Do 


do 


Jannovitch 


24.4 


Aug. 8 
to 


do 


Native ... 

Egyptian 


46.2 


Oct. 28 

1905. 
Nov. 9 


1 

Dallas, Tex 

do 


84.9 


Do 


Pachon 


7 1 70.0 


Do 


do 


Kekchi 


15 1 71.4 


Sept. 24 
Do 


San Antonio, Tc.x 

Calvert Tex 


Shine . 


55 1 78.6 


King 


19 j 57.6 


Do 


do 


Shine 


24 1 51.1 


Do 


do 


Rowden 


17 
37 
14 
17 
18 
11 
15 
12 
19 
27 
18 
92 


.37.8 


Do 


..do 




53.6 


Do 


do 


Triumph 


56.0 


Do 


do 


Tools 


43.6 


Do 


do 


Hawkins 


50.0 


Do . 


...do 


Russell 


61.1 


Do 


do 


.Mien 


.50.0 


Do 


do 


Bohemian 


44.4 


Do . 


...do 


Truitt 


55.9 


Do 


do 

. .do 


Hetty 


87.1 


Do 




53.0 


Do... 


do 


Territory 


56.4 




..als and averages 






Tol 


1,870 


965 


"51.6 


905 


a 48.4 











n Weighted average. 

The general average for all the various seasons and localities 
shows that in squares approximately one-half of all feeding punc- 
tures stimulate proliferation. The highest percentage shown is 75.6 
per cent in "Jannovitch" (an Egyptian variety), at Victoria, Tex., 
on October 22, 1903, while the lowest percentage found was 12.9 



PROLIFERATION FROM FEEDING rUNCTURErt IN BOLLS. 



11 



per cent for "Hetty," at ('alvert, Tex., Sopteiiil)er 24, 11)05. These 
figures show a wide rano;e. Five series of observations show prohf- 
eration in less than 30 per cent of the squares fed upon; three series 
show between 30 and 40 per cent; eight series between 40 and 50 
per cent; six show between 50 and 60 per cent; three !)etween 60 
and 70 per cent. It appears, therefore, that the range, while wide, 
is well balanced, the large majority of o})servations showing between 40 
and 60 per cent. 

PROLIFERATION FROM FEEDING PUNCTURES IN BOLLS. 



Turning now to an examination of proliferation following feeding 
punctures made in bolls, records are presented of the observations 
made during 1905 only. These observations include IS varieties 
and 3 localities. 

Table IL — ProliJ) rot'ion nsii/iiiKifroiiiftcditit/ /iinirfii)(s in hal/.s. 



Date of 
I'Xiiini- 
nation. 



1905. 
Sept. 25 

Do.. 

Do.. 

Do.. 

Do . . 

Do . . 

Do . . 

Do.. 

Do.. 

Do.. 

Do.. 

Do.. 

Do... 

Do.. 
Sept. 27 . 

Nov. U . 
Do.. 
Do.. 



\'ariety. 



King 

Shine 

llowdon. . . 
Nicholson. 
Triumph . . 

Tools 

Hawkins. . 
Russell... 

Allen 

Bohemian. 

Tniitt 

Hetty 

Native 

Territory., 
Shine 



Mit Aflft. 
Pachon. . 
Korean . . 



Locality. 



Calvert, Te.x. . 

do 

do 



.do. 
.do. 
.do. 
.do. 
.do. 



do 

do 

do 

do 

....do 

do 

San Antonio 

Tex. 
Dallas. Tex. . . . 

....do 

....do 



Totals and averages. 



Total 
bolls 
exam- 
ined. 



80 
01 
03 
83 
57 
109 
110 
98 
83 
90 
94 
97 
94 
055 
150 



Total 
locks 
in lot. 



340 
398 
274 
374 
247 
402 
402 
419 
371 
399 
419 
419 
407 
2, 830 
050 

244 

7 
3 



Locks with feeding puncture; 
only. 



With prolifer- Without pro- 
ation. liferation. 



Num- 
ber. 



123 
159 
94 
195 
14'i 
239 
302 
254 
180 
173 
187 
248 
122 
1,251 
104 

04 
5 



3,908 



Per 
cent of 
total. 



30.2 
40.0 
34.3 
52 . 2 
.59. 1 
51.7 
(15. 4 
07.8 
48. 5 
43.4 
44.0 
59.2 
30. 
44.0 
25. 



20.2 
71.4 



Num- 
lier. 



284 
05 



Per 
cent of 
total. 



9.4 

5. 5 

20.5 

10.4 

12.1 

20.8 

0.9 

10.0 

2.0 

5,0 

4.8 

5.5 

10.0 

10.0 

5.7 
0.0 
0.0 



Per cent 
of punc- 
tured 
locks in 
which 
prolifer- 
ation fol- 
lowed. 



79.4 
87.9 
02.7 
83.3 
08.0 
81.0 
70.9 
89.7 
83.0 
95.6 
90.0 
92.5 
84.7 
81.5 
71.0 

82.0 
100. 
100.0 



:81.3 



a Weighted average. 

The bolls examined all showed distinct external signs of weevil 
injury. Among them, however, fully one-fourth of the total number 
of locks were found to have no noticeable internal injury, and ])rob- 
ably a majority of these locks would have matured had the bolls 
been allowed to remain upon the plants. As the ]>olls examined 
were selected especially for weevil injury, it appears that their con- 
dition would probably be worse than the average in fields where 
the weevil has done its worst damage. The figures are of interest, 
therefore, as indicating that even under the most severe conditions 
of weevil injury sufficient seed would still be produced to replant the 



12 PROLIFKRATION IN CONTROL OF BOLL WEEVIL. 

field. While practically one-half of the squares attacked showed 
proliferation, a far greater proportion of the locks attacked by the 
weevil showed a similar formation. 

From these records it appears that 55 per cent of the nearl}^ 9,000 
locks examined received feeding punctures only. Among the locks 
thus injured, an average of slightly over 81 per cent showed distinct 
evidence of proliferation. A comparison with Table I indicates that 
in bolls i^roliferation occurs from feeding punctures in a higher per- 
centage of cases than it does in squares. The records upon Pachon 
and Korean cottons were included in the table because of the special 
interest attached to these varieties, but the data regarding them 
are too meager to be reliable in drawing definite conclusions regarding 
proliferation in them, and they s.iiould be excepted in making a com- 
parison of varieties. It is to be regretted that the two varieties 
mentioned produced so little fruit at Dallas, Tex., that more extensive 
data regarding them could not be obtained, and the fruiting occurred 
so late in the season tluit no bolls could matiu'e. The range in the 
percentage of cases in which proliferation results from feeding punc- 
tures in bolls is not so great as it appears to have been in squares. 
This fact may ])ossil)ly be due to more iniiform climatic and cultural 
conditions, as nearly all the records for bolls were made from mate- 
rial collected in one locality at the same time. 

These records ajipear to the writer to show a remarkable uniformity, 
and to indicate that among the 15 varieties mentioned in the table 
which are most clearly comparable there is little difference in the 
natural tendency to ])roliferate in response to feeding injuries made 
by the weevil in bt)lls. 

INFLUENCE OF DIFFERENT LOCALITIES AND SEASONS. 
OBSERVATIONS ON SQUARES. 

This series of observations was made to determine, if possible, what 
influence difi^erent localities and seasons might have upon prolifera- 
tion in the same variety of cotton. While similar data have been 
secured for a number of varieties, the exhibit following is restricted 
to the two varieties on which the largest immber of observations 
was made, as the conclusions which may be drawn therefrom are 
consecjuently most reliable. In the case of King cotton, different 
seasons as well as localities are represented, while with Shine, difl'erent 
localities are represented at approximately the same time. In com- 
piling this table, both feeding and egg punctures have been included. 
It has seemed desirable also to present the figures showing the effect 
which the proliferation has had upon the weevil stages found. 



OBSERVATIONS ON SQUARES. 13 

Table III. — Proliferation in King and. Shine squares — different seasons and localities. 







o3 


Squares wi 


th proliferation. 


Squares without prolif- 
eration. 


^9 


■3 A 






fe 






















w g 














M 










OT 


C oj 


Variety and 








"5 


> 

"3 










> 
"3 


ai 

■a 


1. 

03 


"Si 

03 •^ 

-o o 


>4- Q> 

.5° 


locality. 




o 




o 










o 


4J 


^ 

^ 




X3 








t-i 


























g 


R 





> 


> 


s^ 


% 

F 




Ol 

o 


1 


'? 


S| 










3 


3 




^ 




(2; 


3 

•A 


Ph 


0) 


O) 


S 


1- 




KING. 




























1904. 




























Victoria, Tex. 


July to Oc- 
tober. 
1905. 


822 


437 


53.1 


87 


14 


13.8 


385 


40.9 


105 





0.0 


100.0 


13.8 


Calvert, Tex.. 


August and 
September. 


218 


124 


50.2 


04 


24 


27.3 


94 


43.8 


01 


2 


3.2 


92.3 


24.1 


Totals and averages . . 


1,040 


501 


a54.0 


151 


38 


a20.0 


479 


a40.0 


220 


2 


n.9 


"95.0 


al9.1 


SHINE. ; 




























[ 1905. 




























Calvert, Tex.. 


August 


229 


122 


53.3 


59 


2S 


32.2 


107 


40.7 


,52 


5 


8.H 


84.8 


23.4 


San Antonio, 
Tex. 


September.. 


443 


212 


47.9 


152 


51 


25.1 


231 


52.1 


178 


18 


9.7 


73.9 


15.4 


Totals and averages .. 


672 


334 


049.7 


211 


79 


a27.2 


338 


"50.3 


230 


23 


19.1 


(i77.5 


al8.1 


General totals and av- 




























verage 




1,712 


895 


052.3 


302 


117 


024.4 


817 


a47.7 


450 


25 


a5.2 


082.4 


"19.2 







a M^eighted average. 

Two rather striking contrasts arc showai l)y a study of the figures in 
this table. First, in the 1,040 King squares examined there were 
found 417 weevil stages, while m 672 Shine squares exammed there 
were found 543 stages. Stated in a way to make the contrast most 
evident, in King there was found an average of one weevil stage for 
each 2.5 squares; in Shine an average of one weevil stage for each 1.24 
squares. That is, in Shine there were almost exactly twice as many 
weevil stages found, in pro]iortion to the number of squares examined, 
as in King. This is a factor, however, which would naturally vary 
widely with the degree of infestation found in the field and it is a well- 
established fact that weevils were much more numerous and injurious 
at San Antonio in 1905 than they were at Calvert, Tex. The second 
striking contrast is to be found in the percent>age of mortality. In 
King squares without proliferation only 0.9 per cent of the weevil 
stages found were dead, while in Shine squares without proliferation 
ten times as large a proportion, or 9.1 per cent, of the stages found 
were dead. Doubtless much of this dill'erence may have been due to 
seasonal rather than to varietal dilTerences, since it appears that in 
King squares at Calvert in 1905 the percentage of mortality was mucli 
greater than at Victoria in 1904. 

In other respects there is a most striking uniformity in the results 
shown. The percentage of squares showing proliferation varies only 
between 49.7 per cent for Shine and 54 per cent for King. The 



14 



PROLIFERATION IN CONTROL OF BOLL WEEVIL. 



av('rai!;(> increase in mortality apparently due to the proliferation 
varies only between 18.1 per cent for Shine and 19.1 per cent for 
Kin^. It appears that the "normal mortality," due to other causes 
than ])roliferation, varies much more widely in different localities and 
seasons than does the increase in mortality attributable to the 
presence of proliferation. 

OBSERVATIONS ON BOLLS. 

Before drawino; any general conclusion from Table III the similar 
records of examinations of bolls should be considered. The same 
varieties and localities are used as in Table III, the only change being 
the inclusion of the examination of King bolls made at Victoria, Tex. 
in 1903. 

Table IV. — Comparison of proJlferaflon in King and Shine bolls in different seasons and 

localities. 



Variety and locality. 



KING. 

Victoria, To.x.. 



Victoriii,, Tex. 
Do 



Cnlvert, Tex.. 

■SHINE. 



Ciilvrrt, Tex 

Smm .Viitonio, Te.x. 



Totals and av- 
erages 



1900. 
Oct. 14 

1904. 
Sept. 5 
Oct. 1 

1905. 
Sept. 25 



Sept. 25 
Sept. 27 



Total 
bolls ex- 
amined. 



G20 
200 



91 
15(1 



Total 
loclcs ex- 
amined. 



865 
843 



398 
{ioO 



1,345 



5,7G8 



Locks with proliferation. 



1.398 



417 

4(18 



234 
422 



3,115 



Per cent 
of total. 



52.4 

48.2 
55.5 

51.7 



58.8 
(14.3 



Weevil 
stages 
jilive. 



37 

189 



33G 



Weevil 

stages 
dead. 



Per cent 

of stages 

found 

dead. 



13.3 
22.2 



30.2 
26.7 



Variety and locality. 



KING. 
Victoria, Tex . . . 



Calvert, Tex . 

.SHINE. 



Calvert, Tex 

San Antonio, Tex 



Totals and av- 
erages 



1903. 
Oct. 14 

1904. 
Sept. 5 
Oct. 1 

1905. 
Sept. 25 



Sept. 25 
Sept. 27 



Locks without proliferation. 



Num- 
ber. 



Per 
cent of 
total 



1,208 



448 
375 



164 
234 



51.8 
44.5 



48.3 



41.2 
35.7 



a 40.0 



Weevil 
stages 
alive. 



Weevil 
stages 
dead. 



Per 
cent of 
stages 
found 
dead. 



0.0 
11.1 



0.0 
11.1 



Percent 

of all 

dead 

stages 
in locks With 

with 1 prolif- 

prolif- eration, 
eration. 



Locks with feeding 
punctures only. 



100.0 
80.0 



75.0 
•J8.0 



159 
104 



With- 
out 
prolif- 
eration. 



Percent 
with 
prolif- 
eration. 



73.7 
67.5 



88.0 
71.0 



"77.4 



" Weiglited average. 



EFFECTS OF CLIMATIC CONDITIONS. 15 

In the case of bolls the conchisions indicated are c{uite simihir to 
those which have been stated for sciuares. The percentage of locks 
showing proliferation in consequence of weevil injury is remarka])ly 
uniform, varyint^; throuojh a rano;e of only 16 per cent in three years in 
three localities and with two varieties. Furthermore, the percenta*i;e 
is almost identical with that shown for squares. 

By far the hif^hest percentao:e of mortality amono; weevils in bolls 
was that found in Victoria in 1903, when an avera<!:e of 40.5 per cent 
of all immature stages was found dead in King bolls. The weather 
during a six-weeks period preceding the examination was exceptionally 
cool and dry, but a heavy rain falling shortly before the examination 
was made may have been a factor in markedly increasing the mortality. 
The percentage of dead stages in locks in the presence of proliferation 
for all the bolls examined averaged 7 per cent higher than it did in 
squares. The percentage of dead stages in locks where no ])rolifera- 
tion occurred was also higher in })olls than in squares by nearly 15 per 
cent, so that the increase in mortality apparently due to proliferation 
was only al^out 13.4 per cent in bolls, whereas it was 19.2 per cent in 
squares. It would appear that in bolls the normal mortality, which 
has no relation to proliferation, is not as clearly influenced by vary- 
ing climatic conditions as it aj)|)ears to be in the squares. 

EFFECTS OF CLIMATIC Ct^NDITlONS. 

In connection with Tal)les III and IV, some statement should })e 
made regarding the climatic conditions prevailing in each locality dur- 
ing the j^eriods in which the observations recorded were being made. 
The statements following are based largely uj^on the published 
Weather Bureau records. We shall begin with the records for Vic- 
toria in 1903, considering first the data for about six weeks preceding 
the examination of bolls made on October 14, 1903, as we may safely 
assume that a large majority of these bolls had been attacked within 
that time. While preceding conditions, es])ecially those regarding 
rainfall, may have had some influence u))on ]>lant growtli (hiiing this 
period, we beli(»ve they may safely l)e disregarded, assuming that the 
conditions inunediately prevailing would be most signilicant in their 
influence u))()n tlie growth of the ])lant, the development of the weevil 
stages in buds and bolls, and the formation of ])roliferati()iL 

The mean average tenq^erature at Victoria dnring S(^))tember, 1903, 
was 77.2° F., which was 3.7° below the normal. During the first thir- 
teen days of October the mean tenq>erature averaged 75. S°, which was 
about normal. Preci])itation during Septenfl)er was very , slight, 
amounting to only 0.54 inch, which was nearly 3 inches below the 
normal. During the first thirteen days of October the rainfall 
amounted to 1 .75 inches, which was 0.42 inch above the normal. 



16 PROLIFERATION IN CONTROL OF BOLL WEEVIL. 

At Victoria in 1904, from July 1 to October 10, the mean tempera- 
ture averaged 80 . 6° F . , which was 1.17° below the normal . During the 
same period the total rainfall amounted to 8.50 inches, which was only 
0.57 inch below the normal. In a general way this season might be 
described as slightly cooler than usual, with the humidity and rainfall 
practically normal . 

No records are available for Calvert, Tex., l)ut the reports from 
Hearne, which is only 8 miles fi-om Calvert, will serve to indicate the 
temperature and rainfall of the latter place with sufficient accuracy. 
During the months of July and August, 1905, the mean temperature 
averaged 82.85° F., which was 2.8° above the normal. No rain fell 
during ISeptember, and during August the rain amounted to only 0.63 
of an inch. For these two months, therefore, the rainfall was 4.33 
inches below the normal. The season may l)e characterized in general 
as exceptionally hot and dry. At wSan Antonio the mean tem]:)erature 
diu'ing these two months averaged 82.5° F., which was 1.6° above the 
normal. During this period the rainfall amounted to 2.31 inches, 
which was 3.35 inches below the normal. Here again the season was 
exce])tionally hot and dry. 

Considering these climatic conditions in relation to the figures given 
hi Table III, the following conclusions would seem to be indicated: 
(1) The percentage of squares which ])roliferate from attack by the 
weevil is not greatly afl'ected by varying conditions of temperature and 
moisture; (2) the increase in mortality due to jjroliferation is not 
greatly affected by the varying climatic conditions as showm for these 
localities; (3) the normal mortality of the weevil which may not be 
attributed to ])roliferation is decidedly greater during especially hot 
dry weather than it is imder cooler and more moist conditions. 

As for liolls, the range in formation of ]:)roliferation in locks fi'om 48.2 
to 64.3 per cent is not unex])ectedly great. The most remarkable fact 
is that the maximum j^ercentage for locks and the minimum percent- 
age for squares occur at the same time, in the same locality, and with 
the same variety. It is ])lain, therefore, that climatic conditions can 
not be held resj^onsible for these contradictory results. The records 
concerning ]K'rcentages of mortality are also too inconsistent to point 
to any constant effect of the climatic conditions upon this particular 
point. The records for "normal mortality" also fail to show any con- 
sistent increase or decrease which may be attributed to exceptional 
conditions of heat or drought. The reason why the records for bolls 
fail to show as consistent conclusions as are indicated for squares may 
probably be found in the comparative difference in the length of the 
growing season for each and in the essential difference in the nature of 
the two sets of organs. Obviously the scpiare would be subject to cli- 
matic changes occurring within only a short ])eriod of time as com- 



EFFECT ON PRULIFERATION OF FERTILIZING SOIL. 17 

pared with the boh, which woukl therefore exliil)it n more eoiii})osit(^. 
resuh of any influential conditions aft'ectinii; it. 

It is proba])ly true that the increased mortality in squares occur- 
ring din-ing hot dry wetither is more directly attrihiital)l(^ to the 
absolute maximiun temperature experienced than it is to the shghtly 
higher mean average temperature prevaiHng. The observatiors 
wliich have l)een here recorded refer only to conditions foinid in 
squares which have ])een attacked hy the weevil, but before tluy 
have fallen to the ground. After scpiares have fallen the influence 
of hot dry weather in largely raising the ])ercentage of mortality 
wherever the scpuires become directly exposed to the sun is unques- 
tionably a still more imjiortant factor in destroying the immatuni 
stages of the weevil. 

EFFECT ON PROLIFERATION OF FERTILIZING THE SOIL. 

In accordance with indiccitions shown by some of the examinations 
of bolls made in lOOo, it was expected that fertilization of cotton 
might ])roduce a considerable increase in the percentage of cases in 
which proliferation followed injury hy the weevil. A test of this 
point required a comparison of a consideral)le munber of varieties 
under similar cultural and soil conditions with check ])lats unfer- 
tilized for each variety. Tests of this nature were institiited at the 
beginning of the season of 1904. Favorable conditions for such 
observations were also furnished by the field experiment at Calvert, 
Tex., during the season of 1005. Fourteen varieties were there grown 
upon Brazos bottom lands. Ejich fertilized plat received an appli- 
cation of 400 pounds of acid phosphate per acre. Conditions in all 
plats were similar with the exception of fertilization. 
31022— No. 5i)— 06 3 



18 



I'ROLIFERATION IN CONTROL OF BOLL WEEVIL. 



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EFFECT ON PROLIFERATION OF FERTILIZING SOIL. 



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20 



PKOLIFERATION IN CONTROL OF BOLL WEEVIL. 



At th(> end of Tal)le Y are ^iven totals and averag'e percentai^es 
for squares and for bolls, hut the differentiation of the result.^ for fer- 
tilized and unfertilized plats is more clearly shown in Tabic VI, whieli 
is ])r<tetieally a snmmary of Table V. In each case the totals show 
the ainount of data iii)on which the conclusions rest. 

Taui.k \[. — Suiiiiiiarij I if (lata appiarnKj in Table V, showiiKj effect of fertilization upon 
formation of proliferation, and the mortality of weevils in squares and bolls. 







3 . 


Ik 

m S 
— '5 


Weevil 
stages 
alive. 


Weevil 

stages 
dead. 


Per cent 

of total 

stages 

dead. 


it 

■- o 


1 


Part of 




z s 


S c 
























plant. 


Plat, on which grown. 


•^ o 


c J3 




o 

+r.s 


u 


o 


p pi 


o 

-g 

1^ 


.5 & 


QJ.S 

ftSH 

o 

§c6 






















































3 =i^ 














>-M+3 


^ 






iz; 
























"* 






■^ 




'' 








Squares 

Po 




1,604 
1,571 


50.5 
49.5 


544 


400 


182 
159 


53 
35 


25.0 
23.8 


10.2 
6.6 


14.8 
17.2 


18.9 


Unfertilized 


508 1 494 


16.2 


Bolls 


Fertilized 


2, 094 
2, 7,34 


60.2 
09.5 


302 22 

286 38 


05 
.52 


2 
3 


17.7 
15.4 


8.3 
7.3 


9.4 

8.1 


17.1 


Do 


Unfertilized 

and averages 


14.5 


Totals 


8. 60.3 


"01.9 


1.040 1,010 


4.58 


93 


021.4 08.4 







" Weighted average. 

An examination of Table VI shows that proliferation follows weevil 
attack in api)r()xiniately two-thirds of the cases in bolls and in 
api)roximately c^ne-half of the cases in scpiares. As between squares 
on fertilized and unfertilized plats, tliere is found a difference of only 
1 per cent, whicli is in favor of the fertilized plats. In the fi<i'ures 
for bolls there is shown a difference of 3.3 ])er cent in favor of the 
unfertilized plats. Even if both these differences were on the same 
side of the account, they are too small to justify the conclusion that 
fertilization with acid phosphate, as used in these ex]K>riments, 
a]i]:»reciably a-ffected the percentage of instances in which ])rolifera- 
tion followed weevil attack. 

From a comi^arison of the mortalit}" percentages it a])]5ears that, 
although among the squares from fertilized })lats thei-e is a slightly 
larger ])ercentage of squares showing jn^oliferation following weevil 
attack, there is, on the contrary, a siualler difference in the average 
mortality which may be attributed to the ])resence of proliferation 
than is found among the squares from unfertilized plats. With 
squares on the unfertilized plats having a slightly smaller percentage 
showing ]:)roliferation there is a somewdiat higher average mortality 
apparently due to the presence of ])r()liferation. In a similar compari- 
s )n with bolls, among those grown on fertilized ground showing pro- 
liferation in 66.2 per cent of the injured locks, tliere was an average 
increase of 9.4 in the ]x^rcentage of mortality, wdiile in bolls growai 
on unfertilized ground showing ])roliferation in 69.5 per cent of 
injured locks the average excess of mortality apparently due to 
proliferation is onh^ 8.1 per cent. 



PROLIFERATION FOLLOWING OVIPOSITION IN SC^TTARES. 21 

The second signiiicant feature of Table VI is that showing the 
effect of fertihzation upon the mortahty of the weevil ^\■itllo^!t regard 
to the presence or absence of prohferation. A coni):)arison of the 
percentages of niortahty shown in the last column of the table 
shows US that in the case of sciiiares there is a difference of 2.7 ])er 
cent and in the case of bolls of 2.(5 per cent in favor of the fertilized 
plats. These differences are so nearly ;dike in both scjiuires and bolls 
as to indicate ' that fertilization, as ])racticed in this case, would 
increase the general average mortality by a small j)ercentage, but 
that this increase was not due to any increase in thv proportion of 
cases showing proliferation. 

One general fact should be stated in regard to held conditions in 
connection with these observations. As has been stated, the experi- 
ment was located in the Brazos bottom. The a])])licati(»n of fertil- 
izer ]:»roduced little apparent difference in the size of ])lants, and the 
difference between varieties was Ijy no means as marked as is usually 
the case. It is possil)le that upon soil naturally k^ss fertile greater 
differences might have ]:)een produced both as regarding varietal char- 
acters and the effect of the application of fertilizer. From the data 
at hand, however, M'e woidd not venture to ])redict that such difl'er- 
ences would result in any greater iiicrease in the mortality o'f the 
weevil than has l)een found in the obs(U'vations here re])()rted. 

PROLIFERATION FOLLOWING OVIPOSITION IN SQUARES. 

The next series of observations to ])e ])resented will deal with a 
comparison of varieties in regard to the formation of ]n"oliferation 
following egg punctures in squares. The com])arison includes obser- 
vations made during three seasons and includes al)out 25 varieties. 
The table shows also the increase in mortality due, a])])arently, to 
proliferation. It is imj^ossible to obtain a close comparison of varie- 
ties in this examination, as the conditions of s«nl, cidtivation, and 
season were so diverse, and the influence of these varying conditions 
can not as yet l)e even closely estimated. In the following tabida- 
tion are included records where there were less than 100 observations 
in the series. It is noticeable that the greatest differences in the 
percentage of sc|uares examined which showed })roliferation occurs 
in cases where examination was made of only a small nund)er of 
scjiuares and late in the season. It is evident that the data in these 
cases are insufficient as a basis for reliable conclusions regarding those 
particular varieties, l)ut the figures may be included in the totals of 
examinations made without materiallvdisturbino- the freneral averasfes. 



99. 



PROLIFERATION IN CONTROL OF BOLL WEEVIL. 



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PEOLIFEEATION FOLLOWING OVIPOSITION IN SQUARES. 23 



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24 PROLIFERATIOlSr IN CONTROL OF BOLL WEEVIL. 

StiKlyins; Tal)le YII with a view to niakino; a com])arison of the 
varieties in regard to their tendency to proliferate in response to egg 
punctures and hirval injuries, it appears that, in cases where one hun- 
dred or more observations were made, the highest percentage showing 
proliferation was 67.7 per cent, found in Allen at Calvert, Tex., on 
September 11, 1905. A previous examination of this variety shows, 
however, only 50.4 per cent, wdiich is almost exactly the average per- 
centage found for all varieties. The average of all observations on 
Allen shows 59.3 per cent having proliferation. The lowest percentage, 
from observations which are closely comparable, was .33.9 per cent, 
found in Sunflower at Victoria, Tex., in 1904. Unfortunately there 
are no other observations upon Sunflower by which this residt may be 
checked to see whether it may be considered as a somewhat constant 
tendency in that variety. This being true, it would not be safe to 
conclude that Sunflower shows the least tendency to proliferate among 
the varieties examined. It should be noted that the average of the 
tliree Egyptian varieties grown at Victoria in 1904 is 52.3 per cent, 
which is slightly above the general average for all varieties examined. 
Considering all examinations for each of the four varieties having 
more than 500 observations each, we find for King 53.2 per cent, for 
Territory 52.8 per cent, for Shine 49.7 per cent, and for Native 45.7 
per cent. Because of the larger number of observations made the 
average percentages shown for these four varieties are undoubtedly 
the most reliable of all those given in the table. It appears to the 
writer fi'om the small variation of 7.5 per cent that the tendency of 
difl'erent varieties to j)roliferate in resj^onse to weevil injury by ovi- 
position or l^y larval feeding is a remarkably imiform character. 
Much more extensive examinations woidd be required to determine 
the ]:)Ositive status of so many varieties in respect to this tendency to 
proliferate. 

SUMMARY OF RECORDS FOR FOUR VARIETIES. 

Examining more closely the portion of Table VII relating to 
mortality, we find that the percentage of mortality in scpiares with 
proliferation ranges from to 50 per cent. The latter figiu-e is found 
in Triumph at Calvert, August 25, 1905. A general average for the 
4,121 squares examined is 22.3 })er cent. For the four varieties- 
Territory, King, Shine, and Native — a closer comparison can be made 
by presenting the figures in tal:)ular form. 



INCREASE OF MORTALITY WITH MORE SEV^ERE ATTACK. 



25 



Table VIII. — Comparison of four rarieties, each hari)t(j orer .'lOO observations in Table VII, 
shoiving average percentages of mortalitu and infuence of proliferation thereon. 



Variety. 



Squares with proliferation, t Squares witliout proliferation. 



Num- 
Ijer of 
squares 
exam- 
ined. 



Territory 1,568 

King 1,525 

Shine ! (i72 

Native : 507 



Num- 
ber of 

squa res 
with 

prolif- 
era- 
tion. 



812 
334 
259 



Niun- 
l)er of 
weevil 
stages 
found. 



763 
250 

28S 
172 



Num- 
I ber of 
Per cent squares 
of stages with- 
found out 
dead. prolif- 
era- , 
tion. 



22.4 

Ig!? 

27.1 
17.5 



Num- 
ber 
weevil 
stages 
found. 



Per 
cent of 
stages 
found 
dead. 



Aver- 
age 
num- 
ber of 
stages 
per 100 
squares. 



740 
713 
33S 
30S 



422 
331 
253 
177 



9.1 
1.7 



Average 
increase 
in rate of 
mortal- 
ity due 
to pro- 
lifera- 
tion. 



18.7 
16.1 
IS.O 
15.8 



111 scjiiares haviiio- ])rolif oration the range in mortality varies 
between 16.7 per cent for Kini;' and 27.1 ]X'r cent for Shine. In 
s(|iiares without prohferation this range is between U.(3 ])er cent for 
King and 9.1 per cent for wShine. The most striking point in this com- 
parison is shown in the hist cohimn of the table giving the average 
increase in mortality due to j)roliferation in each variety. In spite of 
the variations of S.5 and 10. 4 in the preceding j^ercentage columns 
there is shown in the last column a variation of only 2.9 per cent. The 
unfavorable influence of proliferation appears, therefore, to be very 
nearly constant in different varieties, instead of varying widely, as 
early indications had led us to antici])ate that it might do. 

In respect to the rapidity of maturity these four varieties may be 
fairly considered as ranging from the very earliest to the late varieties. 
Rapid maturing or, in other words, "short season" cotton does not 
seem to increase especially either the formation of proliferation or the 
percentage of mortality occurring in the squares. 



INCREASE OF MORTALITY ACCOMPANYING MORE SEVERE ATTACK. 

While only injured scjuares were selected for these examinations 
there was a difference in the severity of the weevil attack in different 
fields. It was evident during the growing season that the field in 
which most of the data for Shine was obtained was being more severely 
injured than any other in which observations were made. The figures 
show some very interesting results of this condition, if, indeed, they 
do not indicate the ex]ilanation for the increased severity of the 
attack. The four varieties may be arranged in the order of the 
increasing j^roportion of weevil stages to number of squares examined. 
The figures for the number of weevil stages found and for the stages 
dead in scpiares without proliferation are reduced to the common basis 
of 1 .OOO squares for convenience in comparing. 



26 



PK()LIFERATI<>]Sr IN CONTROL OF BOLL WEEVIL. 



Increased mortal it>j lit squares irithout proliferation, accompany iiiy increased severity i7i weevil 

attack. 



Variety. 


Number 

of 
squares. 


Number 

of weevil 

stages 

found. 


Number Percent 

of stages of mor- 

dead. tality. 


King 


1,000 
1,000 
1,000 
1,000 


380 
620 
7G0 
810 


6 
17 

91 


1 6 


Native 


2 7 


Territory 


4 9 


Shine 


11 2 







The comj^arison "[iven above shows very clearly the great increase 
in mortality accompanying; increased severity in the weevil attack. 
The (lata here given furnish a very interesting confirmation of the 
conclusions stated in Bulletin No. 51 of the Bureau of Entomology 
(p. 119). The statement most directly confirmed is here repeated. 

By this time the number uf weevils has become so great that the supply of squares is 
insufficient to meet their need for both feeding and oviposition. Selection of squares so 
that these two portions of their attack may l)e kept separate can no longer be exercised.- 
Female weevils are forced to deposit their eggs in squares which liave either received other 
eggs or been largely fed upon, and a much larger proportion of squai'es at this time shows that 
feeding punctures are made in squares having eggs or larva'. By these two factors the 
mortality among young larvie especially is greatly increased. 

An examination of the figures given shows that in Territory cotton 
were found twice as many weevil stages as in King, and among these 
there were 6 times as many dead. In Shine cotton having more than 
twice as many weevil stages as the King, 15 times as many stages were 
dead. 



INCREASED MORTALITY IN SQUARES AND BOLLS DUE TO 
PROLIFERATION. 

Next in order will be a s})ecial study of the increased mortality in 
S([uares and bolls which may be attributed directly to the formation of 
proliferation. The figures for squares and bolls together include more 
than 20,000 observations. In many cases the records are taken fi*om 
data which have been used in preceding tables. 



FORMATIOK OF I'ROLIFERATION. 



27 



Table IX. — Suininanj of obscrrationfi shoivuuj increased inortdlitij i n s<pi(ires and bolls caused 

by proliferation. 



a 
o 


.s 

o . 

.2 -a 

1" 
S 

3 


.2 
.2 

c 

g 

z 


Squares oxaminotl. 


Per cent of 
mortality 
in squares. 


Increase in mortality 
due to proliferation. 


Nunilirr of bolls ex- 
ainined. 


Locks examined. 


Per cent of 
mortality 
in locks." 


v: - 

£2 


c 
ci 


Total number. 

Number with 
prol i fe ra- 
tion. 


5i 

c— . 
"go 


1 

o d 
ft| 


II 


1 
o 


Number with 
prolifera- 
tion. 

Per cent with 
prol i f e r a- 
tion. 


c. 




1902 
1903 


1 


4 ifij; dd 


41.9 


.30 5 


iQ r, 11.0 


1 








1 

1 
9 
2 
14 







246 ! 1,033 
452 1,898 


434 42.0 
995 52.4 


15.0 

28.4 


5.0 10.0 


1903 








12.8 15.6 


1904 
1904 


2,9.54 


1,480 


50.0 


9.6 


.0 : 9.0 




398 1,708 


885 51 . 8 


18.2 


11.1 7.1 


1905 
1905 
1905 
1905 
1905 


4,504 
771 


2,365 

372 

212 

40 


52.5 
48.2 
47.9 
27.8 


i9.6 
28.6 
25.1 
34.8 


5.5 

.3 

9.7 

3.2 


14.1 

28.3 
15.4 
31.6 








! 














4 1 ^dA 












14 
1 




1,802 7,821 


5,069 64.8 


16.7 
14.6 


8.5 
0.0 


8.2 


1905 


1 








82 [ 254 158 \ 62.2 


14.6 


Tota 
era 




] 










Is and 
ges. 


av- 


8,921 1 4,513 


«50.G 


al7.2 ,"3.7 


"13.5 


2,980 12,714 7,541 "59.3 


"15.5 |"9.2 

1 


"6.3 



" Weighted average. 

SUMMARY OF RESULTS OF OBSERVATIONS. 

FORMATION OF PROLIFERATION. 

In the portion of Talkie IX relatino- to squares it should be noticed 
especially that proliferation follows weevil punctures in apj)roximately 
one-half of the squares attacked, either for feedino; or for oviposition. 
The constancy of this ]H'oportion may l)e most clearly shown by bring- 
ing together the general averages relating to this i)oint found in pre- 
ceding tables. 

Average percentage of squares in irhich proliferation follous irceril puitctares as shown in 

several preceding tables. 

Per cent. 

Table I. Feeding punctures in s^iuares — proliferation formed 51. 6 

Tai)le III. Comparison King and Shine .squares — proliferation formed 52. 3 

Tahle V. Squares from fertilized and unfertilized plats — proliferation formed 52. 1 

Table \'\. Squares from fertilized plats — proliferation formed 50. 5 

Table ^T. Squares from unfertilized plat.s — proliferation formed 49. 5 

Table VII. Egg punctures in squares — proliferation formed 50. 5 

Table IX. Increased mortality from proliferation — proliferation formed .^O. (J 

The general aA^erage of all these results shows that ])rolii'eration 
follows weevil attack in 51 \)QV cent of all cases. 

In the portion of the table relating to bolls it a])]:)ears that prolifera- 
tion follows weevil attack in a somewhat higher i)ro])ortion of cases 
than it does in squares. A list of the figures for bolls is here given 
similar to that shown for squares. 



28 > pkolifp:ration in contkol of boll weevil. 

Arcw/c perceniaiieofliH'kx In iHi'ich jiroUffmUonfiillDirs trcevij punctures in hoUs as sliouui in 

srrcrdl pfrcaHiKj lahlis. 

Tiil)lc- II. Fee(lin,<^ punclurcs in Iwll.s. Prulilciiition fornicd in 44.S per cent of total locks 

and in SI.:-} jmt cent of locks actually fed upon. 
Table I\'. Kin<]!; and Shine bolls. Pioliferation foinied in 54 per cent of total locks and in 

77.4 percentof locks actually fed upon. 
Tai)le \'. Fertilized and luifertilized l)()lls. Proliferation formed in (17. S per cent of total 

lucks. 

Thes? fiii'iin^s indicato that j^n'oliiVration is stimulated ])y weevil 
punctures in somewhat nioiv^ than 55 per cent of all locks in bolls 
attacked. The fio;ures in regard to feeding punctures only, show that 
jM'oliforation residts in nearly 80 jxr cent of the locks thus attacked. 
It should be noted here that in many cases the proliferation may have 
been stinuilated l)y secondary causes, such as the entrance of fimgi or 
by decay starting in the open feeding punctures. 

INCREASED MORTALITY OF WEEVIL STAGES DI^E TO PROLIFERATION. 

As would naturally be expected, a study of the increase of mortality 
attributable to proliferation will show a somewhat greater variation in 
the figures for various series of observations than has been found in 
the ]iercentages of instances in which proliferation occurs. Thus for 
scfiiares there is foimd a range of from 9 to 31.B per cent, the general 
average being only about 13.5 per cent. For bolls the range is not as 
great as fcH* squares, being only from 7.1 per cent to 15.6 per cent, 
while the general average increase in mortality in bolls was found to be 
only about 6.3 per cent. This increase is scarcely one-half as great 
as was the increase found in scpiares. 

In neither squares nor bolls is the ])ereentage of mortality sufficiently 
high to appreciably delay the time of maximum infestation by the 
weevil, since, if hibernated weevils survived in their usual numbers, 
the number of weevils developing would be abundantly able to totally 
infest a field by the time the weevils of the third generation had 
(lei)osited a majority of their eggs. However, the fact that prolifera- 
tion does <nndently increase the mortality in l)oth scpiares and bolls 
must bo regarded as a very encouraging sign. It indicates clearly one 
of the most promising lines of investigation in the future development 
of cotton vai'ieties which, by possessing this quality in a still greater 
degree and in condunation with other desirable characters, may prove 
most desirable for culture in the weevil-infested area. So far as our 
])resent knowledge is concerned, we may say that the mortalit}' of the 
weevil is more greatly increased by only two other natural factors 
known — (1) by the effect of long-continued dry weather wdien the 
sun has direct access to the fallen squares upon the ground, and (2) 
by the work of a widely distributed species of native ant, Solenopsi.^ 
(jeminata Fab. 



Bui. 59, Bureau of Entomology, U S. Dept. of Agriculture. 



Plate II. 




Other Insects than Boll Weevil Causing Proliferation. 

Fig. ry. — Bdlhvorm incitiiiK iirolifiTaiinii in txill (al'tiT (juaiiitanee i, sliKlitly enlar.tre<i. 
Fig. 6.— Feeding punctures of young bollworni in sijuare, p)roliferation protruding 
on right side, enlarged two diameters. Fig. 7.— S(jnare borer inciting proliferation, 
slightly enlarged. Figs, t; and 7 original. 



59, Bureau of Entomology, U. S, Dept of Agncultur 



Plate 111. 




Proliferation from Internal and External Stimulation. 

Fig. 8.— Extt'ridV view of aiiparciilly luiiujiirrcl In ill. Ki.tj. 9.— Vievvshovviiiir iirolifcriitiiiii starting 
on inner side nf rarpfl shown in tii^.'s, due tn imnctures of bus.s. Fig. 10.— Proliferation in 
seeds dne to imurturesof Piiiliitdiiid li<i(tt(i. Fi^-. IL— Scrtion of seed proliferating from I\Mita- 
toma punetnre. Fig. Vi.— Boll attacked !)>■ autliraenose, wliieh incited proliferatinn. Figs. 
8-11 sliglitly enlarged; tig. IJ natural size. (Original, i 



PROLIFERATION FOLLOWING ATTACKS OF FUNGI. 29 

STIMULATION TO PROLIFERATION BY CAUSES OTHER THAN 
WEEVIL ATTACK. 

PROLIFERATION .STIMULATED BY OTHER INSECTS. 

Since beginning this study of ])r()Iiferation it has Ijeen noticed 
frequently that it occurs commonly in localities where the weevil is 
not found and ii'om many other inciting causes. Some of the most 
abundant proliferations have been found in bolls and squares follow- 
ing the attack of young bollworms {Ileliotlvis ohsoleta Fab.). (See 
PI. II, figs. 5, 6.) In many cases small columns of purel}" proliferous 
material have b'een found projected from the punctures made by the 
()ressure produced wTthin the square or boll. Similar cases resulting 
from the attacks of young square-borers — Uranotes melinus Ilbn. (PI. 
II, fig. 7) or other Thecla larva?, — are to be found in a probably larger 
proportion of the cases of attack than is generally true with weevils. 
Many species of bugs commonly produce proliferation of internal 
tissues in bolls, though no mark of their puncture can be seen in an 
external examination of the boll (PI. Ill, figs. 8, 9). In this way a 
Mexican bug (Pentatoma ligata Say) does great damage by inciting pro- 
liferation in the seeds (PI. Ill, figs. 10, 11) and preventing the opening 
of the boll. In a series of examinations covering 4,(300 punctures made 
liy this bug 34 per cent of the punctures were found to show distinct 
proliferation. A number of species of native bugs have ])een found to 
incite proliferation in a similar manner. Leptoglossus plvyllo'pus L. 
and Nezara hilaris Say have been studied especiall}^, and proliferation 
has ])een found in a large j^ercentage of punctures 'made by these 
species. In the fields the injury of several species is likely to be so 
similar in nature and effect as to make it impossible to separate the 
work of the various species concerned. Thus Euscliistus servus Say, 
Nezara hilaris wSay, and Thyanta custator Fab. commonly occur 
together. In an examination of bolls attacked by these three species 
])roliferation was found in 52 per cent of the total number of locks 
examined. Other species of Leptoglossus, especially L. ojrpositus Say 
and L. zonatus Dall., have frequently l)een taken upon cotton, and 
undoubtedly they incite proliferatit)n exactly as L. pJiyllopus is known 
to do. Largus succinctus L. also feeds upon cotton bolls and in all 
|)robability incites proliferation, although specific instances have not 
l)een observed. 

PROLIFERATION STIMULATED BY ATTACKS OF FUNGI. 

Ill examining large series of bolls it was found that a small per- 
centage showed distinct and characteristic proliferation on the inner 
side of carpels, which were severely attacked externally by a fungous 
disease of cotton known as aiithracnose. Xo other cause for the pro- 
liferation could be seen, and the number of observations leaves 



30 PROLTFERATION IN CONTROL OF BOLL WEEVIL. 

little doii])t that the anthracnose (PI. Ill, fig. 12) was the cause of the 
proliferation. In an examination of 1,800 bolls 71 locks showed pro- 
liferation from anthracnose. Undonbtedlv various species of fungi 
iind favorable ])laces for attack in the cavities formed by open feed- 
ing punctures, and these also appeared to incite proliferation in 
many cases, though it is possible that their attack accompanied 
rather than caused the proliferation. In still other cases decay 
seemed to l)e the inciting agent, but whether by chemical stimulus 
or in some other way is not known. 

ARTIFICIAL STIMULATION TO PROLIFERATION. 

In order to determine positively whether the formation of prolif- 
eration was connected specifically with weevil attack, a series of 
experiments was undertaken to see if it coidd be produced by artifi- 
cial stimulation without the intervention of any insect. The experi- 
ments, as originally planned, were much more extensive than is shown 
by the figures which follow^, but unfortunately a considerable portion 
of the records was destroyed in the field through the vandalism of 
some unknown person. The records secured are sufficient, however, 
to indicate reliable conclusions to be drawn from the work. 

METHOD OF TREATMENT. 

Punctures of two sizes were made in these tests, the smaller by a 
No. 12 needle, which is the smallest size that is commonly used. 
This needle is not as thick as the proboscis of a weevil, and it made a 
small puncture. The hypodermic syringe needle used woidd make a 
larger puncture than that ordinarily made l)y the weevil for ovi- 
positing, l)ut not as large as is often made in feeding. The needles 
were sterilized in a flame before starting a series of experiments, but 
not })etween the punctures made in the series. 

The "sealing" referred to in Table X, colunm 1, was accomplished 
by using a solution of shellac in alcohol. This was not supposed 
to resemble in nature the mucous secretion used by the weevil in 
sealing her egg punctures, but was simply expected to close the 
punctures a]>]^roximately as tightly as does the weevil. However, 
the shellac solution accomplished this object only partially, as in 
many cases it soon peeled away from the surface of the bud or boll. 
Only a single puncture was made in each square treated, but in more 
than one-third of these scpiares a weevil puncture was present also. 
The eflects of a few chemical solutions when injected into buds or 
bolls were tested also in these experiments (PL IV, figs. 13, 14). 



59, Bureau of Entomology, U, S. Dept. of Agricuitu 



Plate IV. 




Proliferation from Artificial Stimulation. 

Fig 13— Hroliff ration in seeds followinK artilicial stimulation with iiijeelion of water, enlarpred 
three diameters. Fig. 14.— Proliferation in carpel and seed following artilieial treatment with 
aeetie acid. Fig. 1.5.— Prolifenition from carpel and septum enveloi>ing larva in boll. Fig. 
lt;._Loek of boll burst open by [)ressnre of proliferation formed within. Figs. 14-16 slightly 
enlarged. (Original.) 



ARTIFICIAL STIMULATION TO PROLIFERATION. 



31 



RESULTS WITH SQUARES. 

As ill previous tables the records for s([uares and bolls are kept 
separate. 

Table X.~RemUts <if ex peri mentis at Hidalgo, Tex., in producing proliferation in squares 

hg artificial stimulation. 





ci 
P 

■6 

1 


s 


a 




Weevil 
stages 
found. 


Effects of 

artificial 

punctures. 


-3^ 


Treatment of sqiuir;>s. 


Is 

M 

o 


„ 3 

o 


is 

•" o 

P 


0) 

p a 


11 


c 

o . 
+3 +J 

is 

OP, 

p4 


o 


— MS 

+j o 

fe ftp, 


Puncture made with No. 12 sterilized nee- 


5 
5 
4 

7 

3 

10 
4 

5 


5 
5 
4 
7 

3 

10 
4 

5 


1 
1 
2 
2 



5 
2 

3 


12.8 
13.4 
14.0 
12.7 

14.0 

13.4 
12.5 

10.2 


1 
1 
2 
2 



4 

1 

3 












1 


5 


2 



5 
2 

• 3 



5 
4 
5 

3 

5 

2 

2 


100.0 


Puncture made with No. 12 steriUzed nee- 
dle: .-ealcd with shellac 


0.0 


Puncture made with hyoodermic syringe 


0.0 


Pun'>ture made with hyDodermie syringe 
need'e, sterilized; sealed with shellac. . 

Puncture made with hypodermic syringe 
needle: one-half drop of 2 per cent solu- 
tion of formic acid injected: unsealed . . 

Puncture made with hypodermic syringe 
needle: one-half drop" of 2 pcrceni solu- 
tion of formic acid injected; sealed with 
shellac 


28.6 
0.0 

50.0 


Puncture made with hypodermic syringe 
needle; one-half drop of 2 per cent solu- 
tion of caustic potash injected; unsealed. 

Puncture made with hypodermic syringe 
needle; one-half drop of 2 per cent solu- 
tion of caustic potash injected; sealed 
with shellac 


50.0 
60.0 


Totals and averages 


43 

i 


43 


16 


13.0 1 14 1 

1 1 


17 


26 


a 40.0 



a Weighted average. 

It must be remembered that in all cases these artificial punctures, 
thoutrh sealed, resemble feeding punctures of the weevil much more 
closely than they do egg punctures. It is impossible to imitate 
artificially the natural conditions following oviposition, the hatching 
of the egg, and the gradually increasing irritation accompanying 
the growth of the larva. Really the effect of a needle puncture 
upon the tissues penetrated is very different from the feeding punc- 
tures of the weevil. The needle simply crushes the cells, pushing 
them aside from its path, and leaving the cavity it makes more or 
less completely filled with sap and crushed cells. In the weevil 
puncture the work is far more neatly done than it can be in any 
bungling imitation. The sharply toothed mandibles at the tip of 
the weevil's snout cut away the tissues smoothly without crushing 
or injuring adjoining cells, and the material, being eaten, is entirely 
removed from the cavity, leaving it dry and clean with the adjoining 
tissues comparatively uninjured. The difference is really about as 
great as in a case of the accidental amputation of a limb under a 
railway train as compared with the work of a skilled sin-geon. The 



32 PRULIFEKATION IN CONTROL OF BOLL WEEVIL. 

hoalini;- followinu- these two operations inijiiit also lie likened to the 
})roliferation following- artificial and weevil-made punctures. As 
the proba])ility would be greatly in favor of mortification following 
from the untreated railway accident, so would decay be more likely 
to follow a needle puncture in a boll than would the proper healing 
oi the wound by proliferation. The injection of chemical solutions 
by the hypodermic syringe would, in all probability, hinder rather 
than assist proliferation. 

Unfavoral^le as conditions for these tests seem, it appears that 
})roliferation was formed in a perceptible degree in 40 per cent of all 
cases in which artificial ]HUictures were made. The })ro])ortion in 
cases where punctures were left open is slightly greater than where 
punctures were sealed, being 43.7 per cent in the former case, and 37 
per cent in the latter case. In all these cases the proliferation 
was entirely distinct from that caused by larva^ when such were 
])resent. In many instances the proliferation was abu.ndant and 
very })lainly characteristic, in otlier cases there was only a slight 
formation with more or less of decay. The fact that the experiments 
were undertaken at very near the close of the growing season would 
account for the formation of less ])roliferation than might have 
resulted from similar experiments earlier in the season. 

RESULTS WITH BOLLS. 

More extensive exj^eriments were made with bolls than with 
squares in testing artificial stimulation to proliferation. Part of the 
experiments were performed at Dallas and part at Hidalgo, Tex. 
The same methods were used as with squares. The number of punc- 
tures per boll averaged about six. In the experiments at Hidalgo 
it was dillicrdt to find bolls which were wholly free from weevil attack. 
The fidl data from tlie experiments are given in the following table: 



RESULTS WITH BOLLS. 



33 









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34 PROLIFERATION IN CONTROL OF BOLL WEEVIL. 

It should be stated that the attempt to seal punctures by applymg a 
solution of agar-agar was not successful, as upon drying it would peel 
away from the boll, leaving the puncture practically open. The 
sealing with a solution of shellac resulted successfully in most cases. 

Among the 1,103 artificial punctures made proliferation resulted 
in 86.8 per cent. While this percentage is hardly half that found in 
Table II for feeding pimctures of the weevil, it seems fidly as large 
as should be expected from the unfavorable conditions prevailing in 
these tests. Among the 604 unsealed punctures at Dallas prolifera- 
tion resulted in 30 per cent. Among the 223 instances of proliferation 
recorded from these unsealed punctures 62.8 per cent were fi'om 
the inner side of the carpel, 36.3 per cent were in the seeds, and 1 per 
cent in the septa se])arating the locks. A comparison with the 
results from the 38 sealed punctures at Dallas shows in the latter case 
proliferation formed in 44.7 per cent of the punctures. Among the 20 
instances of proliferation resulting, 85 per cent occurred in the carpel 
and 15 per cent in the septa. 

COMPARISON OF RESULTS FROM SIMPLE NEEDLE PLTNCTITRES WITH 
EFFECTS OF CHEMICAL INJECTIONS. 

Comparing next the results from simple needle punctures w^th 
those from chemical injections for the Dallas experiments, it is found 
that from the needle punctures proliferation resulted in 24.1 per cent 
of the total cases, while from the chemical injections it resulted in 45.9 
per cent of cases. It should be stated, however, that decay was much 
more common in the cases of chemical treatment, and in many locks it 
was impossible to tell whether the decay had closely followed or 
whether it had caused the proliferation. 

An examination of the records for Hidalgo shows that proliferation 
resulted from 44.6 per cent of all simple needle punctures and from 
45.1 per cent of those receiving chemical injections. 

COMPARISON OF RESULTS FROM SEALED AND UNSEALED PUNCTURES. 

In a comparison of results from 164 sealed and 630 unsealed simple 
needle punctures it is found that proliferation resulted in 53.7 percent 
of the sealed punctures and in 28.1 per cent of those unsealed. In the 
chemically treated punctures proliferation resulted in 47 per cent of 
the 249 unsealed and in only 40 per cent of the 60 sealed. As these per- 
centages in chemically treated punctures stand in inverse proportion 
to those in simple needle punctures, it does not appear that a well- 
founded conclusion can be drawn as to the influence which the sealing 
of punctures may have upon the subsequent formation of proliferation. 



REARING LARV.E ON PROLIFEROUS FOOD. 35 

CONCLUSIONS. 

Several important and obvious conpti*sio2is may l)o drawn from the 
results of the artificial stimulation of proliferation. Proliferation in 
buds and bolls does not depend essentially for its stinndatioTi ^ipon 
insect injuiy of any particidar kind. It b(>comes unnecessary to assume 
that any irritating secretion is deposited by the weevil with the e^g. 
It has l)een shown conclusively that proliferation may occur entirely 
apart from weevil presence. Proliferation may result from a large 
number of causes, of which the following are noted in this bulletin: 
Weevil feeding punctures, weevil egg punctures, injury l)y the larva 
during its feeding period, bollworm punctures, square-l)orer ])unctures, 
feeding punctures of various bugs, fungous attacks in insect punctures, 
anthracnose, and artificial ])imctures of the bud or boll. 

MANNER IN WHICH PROLIFERATION CAUSES DEATH OF 
WEEVIL STAGES. 

REARING LARV^ ON PURELY PROLIFEROUS FOOD. 

In order to determine whether ])roliferation caused the death of 
larva^ l)y starving or poisoning them, numerous experiments have been 
performed. ITnhatched eggs and larvir just hatched have ])een placed 
in the midst of masses of ]:)iu-ely ])roliferous formation; and these have 
been kept in a tight, moist chamber and transferred to fresh masses 
of proliferation as frequently as necessary to preserve proper condi- 
tions for the larvae. In spite of these frec{uent transferences and the 
somewhat unnatural conditions necessary, it was found that but a very 
small proportion of the larv» died. In some cases the growth was 
completed in masses of ])rolife ration which were coin])letely decayed. 
This condition was allowed to exist in order to test the effect of what 
seemed the most unfavorable food conditions it was ])ossible to pro- 
duce so far as quality was concerned. In one series of ex]>eriments 8 
very young larvas were ])laced in fresh ])roliferous masses. Of these, 1 
died on the first day, but all others reached full growth and ])U])ated 
normally in from nine to twelve days, having fed on nothing ])ut pro- 
liferous material. 

In another series 8 larva> just hatched were started in locks in which 
dead fidl-grown larvte had l)een foimd entirely envelo])ed l)y the ])ro- 
liferation. Surely if ]>roliferation were poisonous, this test should 
prove it, since in each case a larva had l)een previously killed in the 
lock given each young larva for food. 

One larva was accidentally killed in examining the material on the 
fourth day. One larva com])leted its growth and ]>u])ated in the lock 
in which it was originally ])lace(l. Two died and the remaining 4 
also ])U])at(Ml after being transferred to fresh locks from which dead 
larvaj were previously taken. ITnder tht^se most unpromising condi- 



36 PROLIFERATION IK CONTROL OF BOLL WEEVIL. 

tions, therefore, 5 of the 7 larvse tested reached the pupal stage. 
Tliis experiment was performed between November 17 and December 
12, 1905. The larval stage averaged about thirty days in duration. It 
does not follow from the length of this stage that the food conditions 
were even imfavorable, since at that season in bolls the length of the 
larval stage would undoubtedly exceed thirty days under normal field 
conditions. These experiments alone would be sufficient to prove 
that the mortality caused by proliferation is not due to insufficient 
nutrition or to poisonous qualities in the food material of the larvae 
affected. Furthermore, the examination of thousands of squares and 
bolls has shown that in a very great number of cases weevils reach 
maturity m the field on no other food than proliferous cells. 

MECHANICAL CRUSHING THE REAL METHOD. 

The real cause of death in the presence of abundant proliferation will 
become apparent to any one who will take the pains to examine care- 
fidly a few thousand bolls which have been injured by weevil attack. 
In one series of observations, covering 1,800 ])olls, 1,016 weevil stages 
were found. During this examination a partial record was kept of 
those cases in which the cause of death was unmistakably shown, with 
the following result: 

Three adults just alive, l)ut l>aclly deformed by pressure- 
Two pup« just alive, but l)adly deformed by pressure. 
Two pup£e unmistakably crushed to death. 
Twelve larvae unmistakably crushed to death. 

These 19 cases formed nearly 2 per cent of all the stages found. The 
record was not kept by all those engaged in the examination of this 
series of bolls and only the most unmistakable cases were recorded at 
all. It is certain, ther:fore, that this 2 per cent is but a small part of 
the true proportion of weevils which were killed in this way by the 
proliferation. Considering these facts in connection with the conclu- 
sions as to the food quality of proliferous cells, it seems safe to conclude 
that the great nuijority of deaths due to proliferation may be caused 
by the mechanical effect of the formation in first enveloping the larva 
so closely as to prevent its movement (PI. IV, fig. 15), and then the 
continued formation producing sufficient internal pressure (PI. IV, 
fig. 16) slowly but surely to crush to death the foe Vvdiose attack has 
called forth this effort at self-defenso on the part of the plant. Such 
an explanation alone fidly accords with the facts as we know them. 
These observations present to us in a very vivid way an illustration 
of the intensity of the struggle, continually going on between plant 
and insect life. It is a life and death struggle, and it is not always the 
insect that wins. 



3ul. 59, Bureau of Entomology, U. S. Dept. of Agricultur 



Plate V. 




Origination and Effects of Proliferation in Bolls 

Fig. 17.— Proliferation beginning lUKicr farpd linintr. Fig. IS.— Proliferation p^■s^inl,' into 
pupal cell. Fig. 19.— .\ilnlt weevil dcinrmiMl by pres.'iure of proliferation. Fig. -'O.— Pro- 
liferous mass spreading over inner side of carpel. Figs. 17. is. 20 slightly enlarged: lig. 
19 enlarged four diameters, i ( »rii;inal. i 



Jul 59, Bureau of Entomology, U. S, Dept. of Agriculture 



Plate VI. 




Locks Completely Filled by Proliferation. 

Fig. 21.— a, Point of original egg puncture and first proliferation: b, larva crushed l>v proliferatioi 
crowding upon it from all directions. Enlarged four diameters. ( Origiiial. ) 



CRUSHING OF BOLL WEEVIL BY PROLIFERATION. 37 

EXPLANATION OF MECHANICAL ACTION. 

A brief explanation of some additional points regarding the forma- 
tion of proliferation may serve to show more clearly how it becomes 
possible for the plant to literally crush its irritating foe. The explana- 
tion will be given for bolls rather than for squares, though the real 
effect of proliferation is the same in squares as in bolls. 

Proliferation usually begins in the layer of cells adjoining the thin, 
tough lining within each section of the boll. By far the greater part 
of this formation projects through the rupture made by the weevil in 
the tough lining and forms a rather hemispherical mass protriuling 
from the inner side of the carpel (PI. V, fig. 1 7) and pressing into the lock. 
The formation sometimes, though not always, begins before the hatch- 
ing of the egg, which may be moved quite a distance, in some cases, by 
the pressure of the mass behind it. In other cases the egg becomes 
enveloped and the larva hatches into the proliferous mass. In such 
cases it may be destroyed early in life, though it will often make its 
way into the lock, eating its way as it goes. As it feeds the larva is 
continually injuring and irritating tissues capable of proliferation, 
which thus becomes started all around the larva and gradually pushes 
in u])on it from all directions (PI. V, fig. 18). It may happen in this way 
that the space which the larva has eaten out as it grew becomes filled by 
the masses of cells pushing in upon it and the larva can not possibly eat 
away the forming mass rapidly enough to preserve room for itself to 
move (PL V, fig. 20) . Though it may be nearly or quite full grown, it 
can not escape from its narrowing prison and soon becomes so closely 
enveloped as to be unable to move in any direction. It is then an easy 
victim for the relentless pressure of forming cells and is literally crushed 
to death in its prison (PI. VI, fig. 21). 

Very frequently, indeed, instances are to be found in which the plant 
gets a tardy vengeance on the pupa or the newly transformed adult 
(PI. V, fig. 1 9) . Whether death results within a short time or the victim 
is allowed to emerge with only some deformit}'' to tell of its narrow escape 
within the boll, depends largely upon the continiumce of the prolifera- 
tion. Deformed pupte and adults are by no means uncommon and in 
nearly all cases they are luidoubtedly the partial victims of this form of 
plant defense. Many of these specimens have been so deformed by pres- 
sure upon the pupa that the adult can not feed. These would be unable 
to make their escape from the boll did it not hapjjen sometimes that the 
maturing of the boll breaks open the prison cell of these victims and 
turns them out only to perish slowly by starvation. 



38 PROLIFERATION IN CONTROL OF BOLL WEEVIL. 

PROLIFERATION IN PLANTS OTHER THAN COTTON. 

The most definite and abundant observations of proliferation in 
plants other than cotton have been made in two species of peppers 
in connection with the work of the pepper weevil {Anthonomus seneo- 
tinctus Champ.). Proliferation was very distinct in 93.5 per cent of 
the pods of sweet pepper which had been attacked by the pepper weevil. 
It was also found to liave formed in three-fourths of the feeding 
punctures. In pods of the chili pejjpers ])roliferation was found in 
about 38 per cent of those examined and in about 34 per cent of the 
cases of simple feeding punctures. Anu)ng the 300 pepper pods 
examined no trace of mortality residting from the proliferation was 
seen. 

Among other plants no special observations seem to have been 
made to determine the presence or absence of proliferation, but it 
may be allowable to state here that a similar formation, which has 
every appearance of being homologous with proliferation in cotton, 
has been observed by Mr. F. C. Pratt in the pods of garden peas, by 
Mr. C. R. Jones in the pods of cowpeas, by Mr. A. C. Morgan in the 
buds of CaJlirrTioe involucrata, and by Mr. J. C. Crawford in the seed 
pods of mesquite. It would appear probable that when six'cial inves- 
tigation shall be made of the occurrence of ])ro]iferation in other 
plants than cotton it will be found a not uncommon phenomenon in 
very widely separated species of ])lants. " Naturally, it may not 1)6 
expected to occur in response to the great majority of insect injuries, 
since it depends upon a number of coincident favorable conditions, 
and the presence or absence of some other and entirely inirelated 
factor may prevent or obscure its formation even where some of the 
essential favorable conditions are present. 

CONCLUSIONS AS TO NATURE AND SIGNIFICANCE OF 
PROLIFERATION. 

In all cases, whatever the stinmlant, one factor is uniformly essen- 
tial. There nuist be a cell injury which is not sufficiently severe to 
overcome immediately the vital force of the injured organ or tissue. 
Proliferatiorf is simply the manifestation of a natural inherent tend- 
ency of plant cells to respond to an encountered irritation i)y nudti- 
plying or forming new cells. It is evidently a method of self-defense, 
and in the case of cotton the irritation apj^ears to be in nearly 

(1 The possible general occurrence of proliferation as the result of insect attack is shown 
by the followino; quotation lelating to Anthonoimis qnadrigihbns Say on apple, by Prof . 
C. S. Crandall: 

Many of the egg-cavities cut into were found to be more or less completely filled by intruding cell 
masses. These cell masses were quite firm in texture. Sometimes they invaded the cavity from tha 
bottom, but often grew as wart-like excrescences from small areas on the sides of the cavities. In 
several instances dead larvae were found pressed close to the cavity wall by these intruding cell masses. 
(Bui. 198, 111. Exp. Sta.; page 528.) 



CONCLUSIONS KEOARDING PROLIFERATION. 39 

all cases strictly mechanical. The function of ]iroliferation in most 
cases is undoubtedly to repair an injury. 

From the numerous observations dealt with in detail in the preced- 
ing; pao;es a number of conclusions seem to be warranted. The phe- 
nomena considered are very complicated, and consequently only a 
few generalizations are made. 

(1) In a large nund)er of varieties of American u])land cotton 
proliferation has been found to oc-cur in 51 per cent of the cases of 
weevil attack upon squares and in .5.5 per cent of the cases of similar 
attack upon })olls. 

(2) P^liminating a certain jx'rcentage of mortality, which was found 
in cases where no ])r()lifera.tion occurred, the increased rate of mor- 
tality in all W(*vil stages apparently caused b}" proliferation was, 
in squares 13.5 per cent and iii l^olls 6.3 per cent. 

(3) Ordinary variations in climatic conditions seem to have com- 
paratively little effect upon the proportion of injuries })r()liferating, 
although hot, dry weather plainly increased the mortality occurring 
without regard to the jiresence of jiroliferation. 

(4) Contrary to a })revious tentative conclusion, ])ased u])on a 
much smaller mnnber of ol)servations,° the upland American varieties 
seem to l)e somewhat on a. j)arity so far as the tendency toward pro- 
liferation is concerned. 

(5) The application of different fertiliz(n-s to cotton has thus far 
failed to show any tendency toward increasing the proliferation. 

(6) Proliferous tissu{> is not toxic to weevils. Death results in 
most cases in a mechanical way from simple pressin-e. 

(7) Proliferation is caused by the attacks of a niunber of different 
insects, and is easily produced artificially hy needle ])inu'tures. Its 
stimulation appears to be from mechanical irritation, and, conse- 
quently, a secretion on the ])art of the insect does not seem to be 
essential. 

(8) Proliferation occurs commonly in plants other than cotton as 
the residt of hisect attack or from mechanical injury. It has ])een 
noticed in the seed ]>ods of several species of Leguminosa^ and in differ- 
ent species of Capsicum. 

PRACTICAL APPLICATION OF CONCLUSIONS FROM THIS STTTDY. 

The fuudamental purpose underlying all this study of proliferation, 
its causes and its effects, is to learn, if possible, facts which may be 
made of practical use in the effort to grow a profitable crop of cotton 
in the area infested ])y the boll weevil, either by so controlling the 
multiplication of the weevil as to reduce its injury to a sufferable 
((uantity, or b}^ raising the crop so as to avoid the serious injury 
which the pest has shown itself capable of producing under the S3^8tem 

a Bui. Nq. 51, Bureau of Entomp|ogy, U. S. Dept, of Agric, p. 134. 



40 PROLIFERATION IN CONTROL OF BOLL WEEVIL. 

of culture which lias been customarily employed. Many factors must 
be considered in any hopeful solution of this most serious problem. 
With insect pests ounces of prevention are worth many pounds of 
cure. The most promisini^' solution of the weevil problem is undoubt- 
edly found in a combination of the factors restricting" weevil develop- 
ment with those favorino- crop improvement. The facts learned from 
this study of proliferation may be utilized in the class of factors 
restricting weevil development. 

It appears that there is a small variation l)etween ditferent varieties 
of cotton in regard to the proportion of cases in which weevil punc- 
tures stinndate proliferation. It is evident that the presence of pro- 
liferation increases somewhat the percentage of mortality among the 
larvic and pupje in proliferating buds and bolls. The "plain conclusion 
is that the varieties whicii proliferate most freel}" will by that charac- 
teristic tend to restrain the rapid multiplication of the weevil. It is 
probable that varieties ma}^ be developed by repeated selections which 
will be more elective than any now known in restraining weevil 
development in this way; still, this factor alone will probably never 
be of more than secondary importance in reducing the number of 
weevils, as other considerations will inevita))ly be more important in 
determining the most desirable variety to plant. Although the obser- 
vations thus far made have failed to shoAV an}" conclusive etiect of 
fertili/ation of the soil upon proliferation, further investigations 
should l)e made upon this point. Much work would still l)e necessary 
to determine any constant relationshi}) l)etween the formation of pro- 
liferation and climatic conditions. Prohaldy little practical use could 
be made of a knowledge of such climatic relationships if ascertained, 
as the influential factors would always remain beyond the control of 
the cotton planter. 

The tendency to proliferate is by no means a recently acquired char- 
acteristic of cotton; therefore it should not l>e supposed that it is 
any more susceptible to such variation as will render it a still greater 
obstacle to weevil development than are many other characteristics 
wdiich ma}" l)e emphasized with equal or even greater advantage in the 
selection of new strains of cotton for growth in the weevil-infested 
area. Such selections require much time, and we may, therefore, feel 
somewhat encouraged to know that in the long tight yet to come we 
may expect this natural factor to accomplish no less than we have 
found it now doing toward the repression of the weevil. Of course 
complete reliance can never be placed in natural factors for a solution 
of the weevil prol)lein. Doubtless the capacity of the weevil for adap- 
tation to any new conditions which its food plant may present is just 
as great as is any adaptive capacity of the plant. Nevertheless, the 
interference of man is likely to throw the advantage greatly in favor 



CONCLUSION^; FROM THIS STITDY. 41 

of the plant. Natural factors havino- a controllino- intiuence on the 
weevil will do their work no less etieetively if the intelligent assistance 
of the planter l)e given in the planting-, culture, and subsequent care 
of the crop. Repeated and widely varied experience has proven that 
the intelligent planter can, as a rule, so assist natural factors, l)y 
adopting certain changes in his methods of cultivation, as to produce 
a protital>le crop in tlu^ face of conditions which would otherwise have 
insured its failure. 



INDEX 



Page. 

Acid phosphate, in experiment with fertiUzers 17-21 

Adaptation of boll weevil to new ctjnditions 3, 40 

Allen cotton, observations recorded 10, 1 1 , 18, 22, 23, 24 

Ant enemy of boll weevil. See Solenopttis (jcmlnata. 

A ntlionomus quadrigihhus, inciting proliferation in apple 38 

Anthracnose, inciting proliferation 29-30 

Apple, {iroliferation from attack of Anthonoihus quadriglhhns 38 

Artificial stimulation, producing proliferation in scjuares 31-32 

bolls 32-34 

to i)rolifcrati(in 30-32 

Ashmouni cotton, ol)Hervations recorded 10, 22 

Bohemian cotton, observations recorded 10, 11, 10, 22, 23 

r>()ll weevil, stages, num1)er in j)roportiou to squares, King cotton 13 

Sliine cotton 13 

Bolls, climatic conditions affecting proliferation 15-17 

Bollworm. See Ili'Hiilhh olinolehi. 

Bugs, inciting proliferation 29 

Callirrhfi' inrolnrrdfa, proliferation _ 38 

Capsicum, proliferati( m 38 

Carpel, proliferation 8-9, 29, 34, 37 

Climatic conditions, influence on proliferation in bolls 16-17 

scjuares 16-17 

those most fatal to boll weevilstages 16,17 

Cowpeas, proliferation 38 

Crushing of boll weevil larvae by proliferation 36-37 

Decay, following chemical injections 32, 34 

in connection with i)roliferation 28, 34 

Deformed boll weevils, caused by pressure of iiroliferation on pui»a 37 

Dickson c< (tton, observations recorded 10, 22 

Egyptian cotton, observations recorded 10, 23, 24, 33 

Euscli iittus srrnis, probably inciting proliferatii >n 29 

Feeding punctures in bolls, proliferation as result 11-12, 28 

in squares, proliferation as result 10-1 1 , 27 

stimulating proliferati( m 27-28 

Fertilization of soil, effect on proliferation 17-21 

Fungi, inciting proliferation 28, 29-30 

Gelatinization, term applied to proliferation 8 

Hawkins cotton, oI)servations recorded 1 0, 1 1 , 1 8, 22, 23 

Ildlotlus olisoletd, inciting proliferation 29 

Hetty cotton, observations recorded 10, 1 1, 19, 22, 23 

Jannovitch cotton, observations recorded 1 0, 22 

Kekchi cotton, oljservations recorded 10, 23 

43 



44 INDEX. 

Killer Imlls, liiji'li ))()11 wc't'vil luoi'talit y 15 

Kin<r cotton, observations rccordccl. 10, I I , ll.', l.!-ir>, IS, 2l', l.'4-L*(), 27--S, .">;> 

Korean cotton, observations recorded 11, li', L':] 

LaboratoTv work, l)eginnin_<; 7 

Laryiis .snt-ciiu-his, ])roba1)ly i licit iny- ]irolil'eration 29 

Lefynininos;i', ])roliferation 88 

Lrploi/los.siis iipjHisiliix, ])ro))al)ly incitin.tj; pi'oiiferation 29 

/>li>l/l<)jifis, incitin.i:: ]iroHt'eration 29 

zoiKitiiK, probalily inciting- proliferation 29 

Lock, unit of obser\ation in bolls 9 

Mascot cotton, ol)servations i-ecorded 10, 22 

Maximnni infestation, not greatly delayed by j.roliferation 2S 

Mechanical action of proliferation explained 'M 

effect of proliferation .'>()-87 

Mes(|uite, proliferation .SS 

Methods of stndyint; proliferation 9 

Mit Atiti cotton, observations T-ecordcd 10, 1 1, 22, 38 

Mortality, average incl•eas^' from jH'olifeialion, Sliine and King ];>-14, 25 

from ]>roliferation, intlnenced little by climatic comlitioiis 16 

somewhat constant facti ir 14, 16 

increased by proliferation 14, lS-20, 2B-2S, 39, 

<lnring severt' attacks 25-2(5 

normal, occnrring without refeivnce to pioliferation 14, 10-17,39 

varied by climatic conditions 16-17, 39 

not especially increased in "short season" varieties 25 

percentage higher in Shine than in King 25 

range in l»olls 28 

squares 28 

slightly increased by fertilization of soil 21 

Native cotton, ( ibservations recorded 10, 1 1 , 1 9, 22, 23, 24-2t), 33 

Natural i'act()rs, insntticient for control of boll weevil 40 

Nezara. hilarls, inciting proliferation 29 

Nicholson cotton, observations recorded 10, 11, 18, 23 

Normal mortality, effect of climatic conditions 16-17, 39 

Oviposition, stimulating proliferation in scpiares 21-26 

Pachon cotton, observations recorded 1 0, 1 1 , 1 2, 23 

Parker cotton, oliservations recorded 10, 22 

Peas, proliferation 38 

PcYitntoma ligatu, inciting proliferation 29 

Pejjpers, proliferati( m 38 

Poisoning, not effect of proliferation 35-36 

Proliferation, botanical aspects not here considered 2, 8 

causes 35 

definition of term 8 

effect on natural control of weevil 40 

weevil stages 36-37 

evolutionary significance 40 

first j>ublished record 7 

function 38 

general appearance 8 

greater in Egyptian than in rjpland varieties 10,24 

in l)oth plant and animal cells 8 

in plants other than cotton 38 



INDEX. 45 

I'ase. 
Proliferiitiou, iiicthdil of sfmly „ 9 

not connected especially with hyoil weeviF injnry 35, 39 

not increased by fertilization of soil 20, 39 

especially in "short season" varieties 25 

occnrrence more frecpient in hulls than in s(juares 12,38-39 

of similar ciiaracter in hnd and lioil 8 

one of most important natnral factors in control 3, 28 

points of originatii m 8-9 

purpose of study 9 

resnltinii in iiolls from artificial stinuilation 32-34 

S(jnares from artilicial stinndation 31-32 

secondary factor in choice of varieties 40 

stinudated !iy feedimr punctures in l)olls 11-12 

squares 10-11 

fungi and decay 28, 29-30 

tissues reacting most readily 8-9 

Rearing larva:" on proliferous food 35-36 

Red cotton, ol)servations recorded 33 

Rowden cotton, ol;)servations recorded 10, 11 , 18, 22 

Russell cotton, ol)servations recorded 10, 11, 18, 22, 23 

Sealing of punctures, method 30 

influence on proliferation 34 

Peed, proliferation 29, 34 

Septum, ]iroliferatiou 34 

Shine cotton, o))servations recorded 10, 11, 12, 13-15, 18, 22, 23, 24-20, 27-28, 33 

Soil types, range 21 

Sob'uopsis gem iiiala, enemy ( if holl weevil 28 

Scjuare 1)orer. See rV«»o/<>" nu/inux. 

S(|nares, climatic conditions affecting proliferation 16, 17 

Starvation, not cause of death of holl weevils with pi-ol iteration 35-3t) 

Stinudi, causing cells to jiroliferate 8 

Sun, influence on exposed fallen squares 17, 28 

Suntli iwer cotton, observations recorded 22, 24 

Territory cotton, observations recorded 10, 11, 19, 22, 23, 24-26 

Texas wool cotton, oljservations recorded 33 

Thecia larv;c, inciting proliferation , 29 

Tln/aiild rnxhilur, prol)ably inciting proliferation 29 

Tissues, <'hange following boll weevil attacks 37 

Tools cotton, observations recorded 10, 11, 18, 22, 23 

Triumi)h cotton, observations recorded 10, 11, 18, 22, 23, 24 

Truitt cotton, observations recorded 10, 11, 19, 22, 23 

rrdtioh's nicliiiits, inciting proliferation 29 

Weather Bureau, use of records sliowing climatic t'onditions 15 

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